1. Field of the Invention
The present invention generally relates to quick-release mechanisms for attaching and removing a bicycle wheel to and from a bicycle frame without the use of tools and, more particularly, is concerned with a quick-release apparatus with improved features that promote proper attachment of the bicycle wheel to the frame.
2. Description of the Prior Art
Heretofore, bicycles have employed various quick-release mechanisms designed to enable wheels to be removed quickly and easily in order to repair the wheels, to more readily transport the bicycle by a vehicle, and to prevent theft of the wheels. Different quick-release mechanisms known in the prior patent art are exemplified by the ones disclosed in U.S. Pat. No. 4,033,627 to Morroni, U.S. Pat. No. 4,079,958 to Segawa, U.S. Pat. No. 4,400,038 to Hosokawa, U.S. Pat. No. 4,763,957 to Poehlmann et al, U.S. Pat. No. 4,789,206 to Ozaki, and U.S. Pat. No. 4,805,941 to Downing et al, U.S. Pat. No. 4,906,053 to Kawai, U.S. Pat. No. 4,964,287 to Gaul, U.S. Pat. No. 4,971,397 to Nichols et al, and U.S. Pat. No. 5,005,390 to Giannini et al.
One design of a quick-release mechanism, widely used on bicycles, especially in conjunction with front wheels, and disclosed in many of the patents cited above, basically employs an elongated skewer or drawbar shaft, a cam lever assembly, and a cap nut. The bicycle frame has front and rear forks for mounting the bicycle wheels. The front fork for mounting the front wheel includes a pair of blades or tines having mounting slots defined at their lower tips which open in a downward direction. The front wheel includes a hub and axle assembly having a wheel hub and a hollow axle for rotatably mounting the wheel hub across the space between the front fork tines. The axle has opposite ends which extend beyond opposite ends of the wheel hub and fit within the mounting slots at the lower tips of the fork tines.
The drawbar shaft of the quick-release mechanism is removably mounted through the hollow axle of the wheel axle assembly and extends from opposite ends of the axle. The cam lever assembly of the quick-release mechanism is mounted at one end of the drawbar shaft extending from one end of the axle. The cam lever assembly includes a body slidably mounted for axial movement on the one end of the shaft and a cam lever pivotally mounted to the body for producing axial movement of the body toward and away from the cap nut on the other end of the shaft. The cam lever has an outer lever arm and an inner cam element rigidly attached to the outer lever arm and engaged with the body. Pivotal movement of the outer lever arm rotates the inner cam element relative to the body producing axial movement of the body.
The cap nut of the quick-release mechanism is threaded on the other end of the drawbar shaft extending from the other end of the axle. With the cap nut threadably positioned at a proper location from the axle assembly on the other end of the drawbar shaft, the wheel can be properly attached between the tips of the front forks of the bicycle frame by pivoting the lever arm of the cam lever assembly from a disengaged position to an engaged position. As the lever arm pivotally moves from the disengaged position toward the engaged position, the cam element rotates causing the body to axially move toward the cap nut. Such movement ceases when both the cam lever body and the cap nut engage the outer sides of the respective adjacent tips of the front forks. Then, completion of pivotal movement of the lever arm to the engaged position imposes a force on the drawbar shaft that places it under tension, causing the cam lever body and cap nut to clamp the tips of the front forks against the opposite ends of the axle and thereby secure the bicycle wheel to the frame.
There is a correct procedure or order of steps to follow for ensuring proper attachment of the bicycle wheel to the frame. First, the lever arm is initially placed at the disengaged position. Next, the cap nut is rotated relative to the shaft to place it at a desired location along the shaft which is the desired distance from the one end of axle that will result in the desired tension being applied to the drawbar shaft when the lever arm reaches its engaged position. The lever arm is then pivoted from the disengaged position to the engaged position.
Bicycles employing the above-described quick-release mechanism are used by a wide variety of persons. Most users are very interested in proper use and care of their bicycles and thus will have the interest and take the time to learn how to properly operate the quick-release mechanism. However, some users, unfortunately too many, are careless in this regard and will fail to learn nor to follow the above-described correct procedure for properly attaching the wheel.
Oftentimes, these latter users will first pivot the lever arm from the disengaged to engaged position and then threadably tighten the cap nut toward the engaged lever arm in an attempt to apply enough tension to clamp the axle between the fork tips. By following this incorrect procedure, insufficient tension will be imparted in the drawbar shaft to securely clamp the wheel axle between the frame fork tips.
At other instances, these latter users will not threadably adjust the cap nut relative to the drawbar shaft at all, but instead will rotate the lever arm while at its disengaged position to cause rotation of the drawbar shaft in a manner that will tighten the cap screw. Thereafter, the lever arm is pivoted from the disengaged position to the engaged position to apply tension to the shaft. By following this incorrect procedure, the drawbar shaft typically becomes either over-tensioned or under-tensioned. Over-tensioning of the drawbar shaft leads to its fracture and the failure of the quick-release mechanism. Under-tensioning of the drawbar shaft leads to inadequate clamping of the frame fork tips against the wheel axle. Both over-tensioning and under-tensioning of the shaft in such manner eventually result in unexpected detachment of the wheel from the bicycle frame.
At the present time no satisfactory design has been proposed that will solve the problem of how to ensure that all users will learn and follow the correct order of steps in operating the quick-release mechanism to properly attach the wheel to the bicycle frame. Consequently, a need urgently exists for an improved design of the above-described quick-release mechanism. The improved design will be one that promote practices which are reasonably expected to lead to proper mounting of the bicycle wheel to the frame.